Backfire - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
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post #1 of 16 (permalink) Old 02-25-2011, 06:53 PM Thread Starter
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Backfire

Greetings!

Two things: 1) I've recently developed a backfire even at start-up. One guy suggested racing fuel to clean out the system. What do you guys think?

2) I can't get a standard plug socket from Sears on my spark plugs. Do I need a special spark plug socket to do the change myself? My bike is a '94.

I'm not much of a mechanic, but a couple years ago some of you pointed me to a solution that was right on the money for my cycle. I'm hoping you can help again.

Thanks either way.

Daryl
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post #2 of 16 (permalink) Old 02-25-2011, 07:14 PM
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You need a thin walled socket. I had to grind one down to fit. I would not go with racing fuel. I would go with sea foam or some other product made for carb cleaning while riding.

02 honda sabre 1100
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post #3 of 16 (permalink) Old 02-25-2011, 08:07 PM
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X2 on Sea Foam!

I'm keepin' all the left over parts. I'm gonna use 'em to build another bike!
_____________________________________________
"Black Beauty"
1989 VN750 acquired December, 2008, 6,711 miles
Currently 23,298 miles

Old Blue
2001 Honda CMX250 Rebel acquired July, 2008

1987 VN750 project bike, acquired August, 2009, 33,000 miles and balancer sticking out of the case, currently awaiting attention and parts
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post #4 of 16 (permalink) Old 02-25-2011, 09:49 PM
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backfire at startup is caused by one of three things... either a problem with the ignition system, a vacuum problem, or a carb problem, or it could be a combination of them all. I personally would start with the easiest and cheapest to fix which would be vacuum leaks around the carb boots, and the carb vacuum ports, from there I would get into the ignition system... make sure both cylinders are firing on all four plugs. usually with the plugs not firing it is as simple as a plug on one of the coils came loose, or the pickup coil assembly is grounding out. Both are easy and cheap (if not free) to fix.
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post #5 of 16 (permalink) Old 02-26-2011, 10:07 AM Thread Starter
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Thanks for the help. I'll try to get a thin walled socket and change the plugs, since I wanted to do that anyway, then check the other items mentioned. I have sea foam in the tank now, awaiting a little warmer weather to ride. We had some snow last night. I appreciate all your comments.
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post #6 of 16 (permalink) Old 02-26-2011, 11:37 AM
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Make an investment for the best and get 4 NGK Iridium spark plugs. (DPR7-EIX...I think that is the model#) Much easier starting of the bike....and better spark combustion. They are worth more to the bike reliability then you will pay for them. Almost everyone on here will recommend this upgrade. Also when it comes to battery replacement go with a NON- Chinese made AGM Maintenance free battery. That style of battery is also worth way more than the little extra money that you will pay for it.
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post #7 of 16 (permalink) Old 02-26-2011, 12:28 PM
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Quote:
Originally Posted by niterider View Post
You need a thin walled socket. I had to grind one down to fit. I would not go with racing fuel. I would go with sea foam or some other product made for carb cleaning while riding.
Actually, it's an 18mm deep metric socket. Works great!!


'94 VN 750 17k mi. Aqua, Memphis shade.
Acquired 2/2011
Oiled
Tank cleaned
New Fork seals
Marbled
Idle jets-RT-3.0, Lft-2.5 turns
Sea Foamed
New Batt for grins
Stupid hose in the rt ear found and fixed
Major clutch adj.
New Petcock
New Shimko tires
De-goated before I got it.
Iridium plugs
YEA! New choke cable!!
Gonna do the Spline Lube soon(Chged tires before I found this site)

Replacement for my FXDWGI
Why didn't I find these before I spent $22 grand!!
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post #8 of 16 (permalink) Old 02-26-2011, 12:44 PM
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Quote:
Originally Posted by dynajim View Post
Actually, it's an 18mm deep metric socket. Works great!!
Still has to be thin walled as NR said... a standard US made 18mm deep well socket is too thick... now the cheap Chinese 18mm sockets are thin walled.
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post #9 of 16 (permalink) Old 02-26-2011, 03:07 PM
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Yup. Those would be the ones;-) Got mine @ Auto Zone. I had the same prob. 20G's in tools and I didn't have a plug socket that would fit. Till then!


'94 VN 750 17k mi. Aqua, Memphis shade.
Acquired 2/2011
Oiled
Tank cleaned
New Fork seals
Marbled
Idle jets-RT-3.0, Lft-2.5 turns
Sea Foamed
New Batt for grins
Stupid hose in the rt ear found and fixed
Major clutch adj.
New Petcock
New Shimko tires
De-goated before I got it.
Iridium plugs
YEA! New choke cable!!
Gonna do the Spline Lube soon(Chged tires before I found this site)

Replacement for my FXDWGI
Why didn't I find these before I spent $22 grand!!
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post #10 of 16 (permalink) Old 02-26-2011, 03:50 PM
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Before i replace my battery, i would occaisionally get a backfire when trying to start. all is fixed now, but my question is, does a backfire cause any damage? I know on my boat, with a Holly 4160, a backfire requires the replacement of the powervalve. anything like that on the bike?

1986 Vn750
18,800 miles, and counting
Bone Stock
New cam chain tentioners
all fluids changed
Spline Lube
windshield
Engine Guard
B-stone S11 RWL-stock sizes
*wanted*
New grips

2001 Vn750
13,100 miles, and counting
spline lube
Bridgestone S11 100/90
Shinko 170/80
rear end oil change
aftermarket mirrors
windshield
otherwise all stock
*anticipated mods*
Engine Guard
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